[all-commits] [llvm/llvm-project] 1de3e7: [ARM] Improve handling of empty VPT blocks in tail...

[David Green via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 1de3e7fd620bc9db2df96a12401bde4bde722785
      https://github.com/llvm/llvm-project/commit/1de3e7fd620bc9db2df96a12401bde4bde722785
  Author: David Green <david.green at arm.com>
  Date:   2020-12-14 (Mon, 14 Dec 2020)

  Changed paths:
    M llvm/lib/Target/ARM/ARMLowOverheadLoops.cpp
    M llvm/test/CodeGen/Thumb2/LowOverheadLoops/vpt-blocks.mir

  Log Message:
  -----------
  [ARM] Improve handling of empty VPT blocks in tail predicated loops

A vpt block that just contains either VPST;VCTP or VPT;VCTP, once the
VCTP is removed will become invalid. This fixed the first by removing
the now empty block and bails out for the second, as we have no simple
way of converting a VPT to a VCMP.

Differential Revision: https://reviews.llvm.org/D92369